Frost and Ice on Windows

During colder temperatures you may notice that there is a fog or an accumulation of frost and ice on the bottoms, corners and between the sliders of your windows. This is due to condensation forming on your windows and could lead to damage if not addressed.

WHY IS MY WINDOW COVERED IN CONDENSATION?

Condensation on interior windows occurs naturally when air with sufficient moisture meets a cold window surface.

Air can only hold a limited amount of water vapor at any given temperature; this is called Relative Humidity. As warm room air meets a cool window surface, the air cools and loses the ability to hold water. If the moisture in the air is high enough, or if the surface of the glass is cool enough, the water in the air will deposit on the glass surface. This is called condensation. Condensation typically appears on windows before any other surface because windows generally have the least insulation value on an exterior wall and react the quickest to changes in outdoor temperature. When outdoor temperatures drop, you can reduce condensation in your home by limiting the amount of moisture in the indoor air. If you have a humidifier, reduce the setting to help decrease moisture and try to limit routine activities such as cooking, showering and laundry.

This chart is a guide to assist you with where your humidity levels should be, based on the outside temperature:

HOW CAN I REDUCE CONDENSATION IN MY HOME?

ROUTINE ACTIVITIES:

• Shut off or adjust Humidifiers
• Take shorter showers
• Cover boiling pots of water
• Hang less clothes out to dry
• Avoid storage of firewood indoors

CREATE BETTER AIR CIRCULATION

• Open blinds or window coverings
• Direct heat to your windows, do not cover vents below windows
• Move furniture so it is not touching outside walls
• Leave doors open in home to help circulate airflow
• Remove items from exterior window wells

INCREASE VENTILATION IN THE HOUSE

• Turn your HRV (Heat Recovery Ventilation) on and set it to run 20 minutes/hour, or intermittently (green light)
• If you have a ventilation switch instead of an HRV, turn your ventilation system on and leave it on (day
• and night) during cold temperatures. This will help circulate the air regularly. The ventilation switch will
• be next to the thermostat and should be labeled
• Run your hood fan during and after cooking for approx. 10–20 mins
• Run your bathroom exhaust fans during and after showering for approx. 30 mins
  • If your bathroom fan is leaking, run it for 4–6 hours, then shut off and monitor